AC Switch mechanism of the ball contact type

Abstract

An AC switch mechanism utilizes a ball contact to which generally linear motion is imparted by a rockable actuator having a spring providing downward contact force and a spring acting ball pusher leg to provide a snap action. In a single pole configuration disclosed as a typical and basic embodiment of the switch, the ball contact in one extreme position engages and extends as a conductive bridging element between bared conductor wires of an electric cable. The cable thus dispenses with the need for assembling separately made switch terminals with the other components of the mechanism. When moved from the "on" position to its other extreme, "off" position, the ball moves onto sloping ramps having a slight, gradual inclination relative to the lengths of the conductor wires. The construction offers a slow break to provide a minimum arc length before the zero point of the AC cycle, a characteristic of great importance in the design and operation of AC switches. Further benefits are obtained by providing a simultaneous two-point break to divide the arc and therefore reduce the arc's outward extension and tracking of the adjacent areas. The design is additionally effective to produce a fast bounce, free make to minimize contact deterioration caused by arcing at the "make" point of the switching cycle. The need for silver alloy contacts is eliminated by providing a continuously moving point of arc termination which cools the contact surface, minimizing the volume of vaporized material, and condenses out the copper vapor during the zero point of the half cycle.

I claim: 
     
       1. A switch comprising: (a) a housing of electrically insulative material having a contact support wall;   (b) stationary electrical contact means supported upon and extending along said wall;   (c) contact-supporting rib means on said wall having ramps inclined at a slight angle in respect to said stationary contact means;   (d) a ball contact movable along said wall from a first, "on" position in which it engages the stationary contact means and a second, "off" position in which it leaves the stationary contact means via said ramps and comes to rest upon the rail means in spaced relation to the stationary contact means; and   (e) actuator means movably mounted in the housing for biasing the ball contact between the "on" and "off" positions thereof.   
     
     
       2. A switch as in claim 1 wherein the stationary contact means comprises a pair of elongated, parallel, conductive rails, the ball contact extending in bridging relation to said rails. 
     
     
       3. A switch as in claim 2 wherein the rails are the stripped ends of an electric cable. 
     
     
       4. A switch as in claim 2 wherein said rib means comprises a pair of ribs electrically insulative material extending in parallel relation to said rails, said ball contact extending in bridging relation to and being supported upon said ribs. 
     
     
       5. A switch as in claim 4 wherein the distance across the locations at which the ball contact engages the ribs is greater than the distance across the locations at which the ball contact engages said rails. 
     
     
       6. A switch as in claim 4 in which the ribs are formed with ledge portions receiving the ball contact in the "off" position of the switch, each of said ribs including a ramp portion extending in close proximity to one of said rails. 
     
     
       7. A switch as in claim 6 wherein the rails are disposed between the ribs. 
     
     
       8. A switch as in claim 7 wherein the distance between the points of engagement of the ball contact with the ribs is closer to the length of the ball contact diameter than is the distance between the points at which the ball contact engages the rails. 
     
     
       9. A switch as in claim 6 wherein the actuator means moves across dead center when biasing the ball contact between said "on" and "off" positions. 
     
     
       10. A switch as in claim 9 wherein the actuator includes a handle and compression spring means interposed between the handle and the ball contact. 
     
     
       11. A switch as in claim 10 wherein the spring means in integral with the handle. 
     
     
       12. A switch as in claim 11 wherein the handle and spring means are of molded plastic material. 
     
     
       13. A switch as in claim 12 wherein the spring means comprises an end portion engaging the ball contact and a pair of resiliently yieldable spring elements connecting the end portions to the handle. 
     
     
       14. A switch as in claim 13 wherein the spring elements are respectively formed approximately to a V shape. 
     
     
       15. A switch as in claim 14 wherein the V shaped elements open outwardly from each other. 
     
     
       16. A switch as in claim 10 wherein the actuator further includes flexible stops integral with the handle at opposite sides of the spring means and adapted to engage respectively opposite walls of the housing when the handle is operated between said "on" and "off" positions. 
     
     
       17. A switch as in claim 16 wherein said spring means is V-shaped and wherein said spring stops load up against the "V" shaped spring means to force it past dead center during actuation. 
     
     
       18. A switch as in claim 16 wherein the flexible stops are formed as plastic arms molded integrally with the handle and having distal ends that engage the walls of the housing to flex the arms and thereby promote quiet operation of the switch. 
     
     
       19. A switch as in claim 18 in which said arms force the spring to bias the ball past dead center. 
     
     
       20. A switch as in claim 2 wherein at least one of the ramps and actuator means respectively, is designed to impart a slight rotation of the ball about its vertical axis, whereby a continuously new contact surface on the ball presents itself to the conductor rails. 
     
     
       21. A switch as in claim 20 wherein the ball contacts a different, new, part of each of the conductors responsive to wear of the ramps. 
     
     
       22. A switch as in claim 2 further including electrically insulative barriers disposed between the ball and the rails in the "off" position of the ball contact.